In order to improve hemodynamic results, aortic annulus enlargement has been recommended as an adjunct to valve replacement with the Hancock bioprosthesis. In order to determine a need for this additional procedure, postoperative cardiac catheterization data from 73 patients were reviewed. All patients underwent aortic valve replacement with Hancock standard orifice bioprostheses; annulus enlargement was not employed. Residual peak systolic gradient or small effective valve orifice area did not preclude satisfactory clinical improvement. Small diameter Hancock bioprostheses demonstrated acceptable clinical and hemodynamic function when limited to patients with small body surface area. In these instances annulus enlargement is rarely necessary.